During the starter scenario, playing as the Union, the 5th Wisconsin Hancock's Brigade) went Out of Command even though it was within Hancock's command radius. I moved the 5th Wisconsin within 2 hexes of Hancock, but it was still marked OOC. What am I missing? I thought for a unit to be "in command" all they needed to do was be in the command range of their Brigade Commander.

During the starter scenario, playing as the Union, the 5th Wisconsin Hancock's Brigade) went Out of Command even though it was within Hancock's command radius. I moved the 5th Wisconsin within 2 hexes of Hancock, but it was still marked OOC. What am I missing? I thought for a unit to be "in command" all they needed to do was be in the command range of their Brigade Commander.

As per Section 6.10 of the Manual:

"Units and groups that are out-of-command can be recognized by the “(OOC)” after their name in the Unit Roster display. This problem of OOC units is easily anticipated: you can click on the Command Radius Toggle – the small, circular button just above a commander’s portrait – in order to see all the hexes that are within the commander’s command radius marked on the map with a red outline, revealing where the commander’s subordinate commanders (or brigades, for a brigadier commander) should move in order to remain in command."

So, be sure to double check the Unit Roster display before continuing.

However, I can find nothing under Rule 9.3 - Zone of Control - that confirms (one way or the other) the effect of an enemy ZOC on one's own commander's command radius. Perhaps, Gil (or other) will provide a heretofore unwritten game manual clarification?

Yep, re-read that section of the manual. However, as I said in my original post, I moved the OOC unit within 2 hexes of the Brigade commander and the unit was still OOC. I'm thinking maybe it has something to with morale. The manual seems to indicate that all you have to do to keep a unit "in command" is make sure the unit is in the command radius of their superior unit.

Yes, perhaps, the BAB programmer has implemented a heretofore undocumented "Inebriated Brigadier" rule that never got into the manual, which recreates the occasional impediment to command and control that some brigadiers on occasion visibly suffered from due to excessive imbibing on the battlefield? The problem with this one of many possible theories is that an intoxicated commander would prefer to remain far behind with the supply wagons where it was much safer to exercise 'command'.